Field of the Invention
Exemplary embodiments generally relate to a light diffusing lens and a light emitting device including the same. In particular, exemplary embodiments relate to a light diffusing lens of a light emitting device, which is suitable for a backlight unit of a surface lighting apparatus and a liquid crystal display.
Discussion of the Background
A typical display device includes a direct type backlight unit in which a plurality of light emitting elements is arranged at certain intervals under a substantially plate-shaped object, such as a liquid crystal panel or a diffusive plate, to illuminate the plate-shaped object. In order to achieve uniform illumination of the plate-shaped object using only the plurality of light emitting elements, a large number of light emitting devices must be densely arranged, thereby causing increase in power consumption. Moreover, if there is deviation in quality between the light emitting elements, the plate-shaped object exhibits non-uniform brightness. In order to reduce the number of light emitting elements, a light diffusing lens is provided to each of the light emitting elements to promote light diffusion. In this structure, a light diffusing lens and at least one light emitting element corresponding to the light diffusing lens constitute one light emitting device.
A light emitting device including a typical light diffusing lens has a beam angle distribution of about 80° or less with respect to an optical axis coincident with a central axis of the light emitting device. Although a conventional backlight unit includes a light emitting device having a light diffusing lens, the conventional backlight unit is required to maintain a sufficient distance between the light emitting device and a diffusive plate in order to provide uniform surface light to a liquid crystal panel, thereby causing limitations in achievement of a slim structure.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art